Cathodic protection systems commonly make use of packaged linear anodes having a variety of shapes (e.g., round, flat, or other shapes) and may be either a polymeric cable anode or a Mixed Metal Oxide (MMO) wire anode housed inside a braided or unbraided fabric housing filled with conductive backfill, such as coke-breeze. These commercially available fabric-based linear anodes are similar in design and function. One particularly useful packaged linear anode for cathodic protection systems is commercially available from Matcor, Inc., the assignee of the subject invention, under the trademark SPL-FBR. That anode assembly basically comprises a fabric housing through which an electrical conductor (i.e., the anode) passes. The fabric housing is filled with coke-breeze, so that the coke breeze surrounds the anode, with the anode being centered therein. An external non-conductive braiding, such as PVC coated high strength yarn, is disposed about the fabric housing for the entire length thereof.
In order to provide cathodic protection to an aboveground steel storage tank it is a common practice to dispose a long anode assembly in a spiral or concentric pattern so that it lays flat on a prepared flat surface below where the steel tank bottom will be located. Then a layer of sand is backfilled over the anode assembly. For applications where there may be less than six inches between the anode and the steel bottom of the tank, the use of an anode assembly having a fabric housing filled with a conductive back-fill, such as the coke-breeze, can prove problematic. In this regard, the close proximity of the steel tank bottom with the coke breeze embedded anode may result in current leakage creating a hot spot or even shorting out the anode. Thus, for such shallow backfill AST applications Matcor, Inc. makes it a practice to use of a bare wire anode in a hollow non-conductive mesh housing without any conductive backfill. The conductive wire making up the anode of such an assembly is typically unwound from a reel, so that when the anode assembly is disposed on the flat prepared surface, it tends to attempt to reassume the anode's previously coiled state. This action necessitates staking the anode assembly down or otherwise providing some means to hold it as flat as possible on the prepared surface so that all portions of the anode assembly will be located approximately the same distance from the tank's bottom, thereby providing uniform cathodic protection to the tank's bottom. Needless to say it is difficult, and time consuming to lay out the anode assembly on the prepared ground surface and ensure that it is maintained flat to that surface to ensure maximum and uniform separation of it from the tank bottom.
Accordingly, a need exists for an anode assembly which can be used in shallow backfill applications for effectively protecting aboveground storage tanks and which can be readily placed in a desired flat position on a prepared surface. The subject invention addresses that need.